<template>
    <div class="file-upload">
        <div class="upload-area" :class="{ 'is-dragover': drag && isDragOver }" v-on="events">
            <slot v-if="isUploading" name="loading">
                <button disabled>正在上传</button>
            </slot>
            <slot name="uploaded" v-else-if="lastFileData && lastFileData.loaded" :uploadedData="lastFileData.data">
                <button>点击上传</button>
            </slot>
            <slot v-else name="default">
                <button>点击上传</button>
            </slot>
        </div>
        <input ref="fileInput" type="file" :style="{ display: 'none' }" @change="handleFileChange">
        <ul :class="`upload-list upload-list-${listType}`" v-if="showUploadList">
            <li :class="`uploaded-file upload-${file.status}`" v-for="file in filesList" :key="file.uid">
                <img v-if="file.url && listType === 'picture'" class="upload-list-thumbnail" :src="file.url"
                    :alt="file.name">
                <span v-if="file.status === 'loading'" class="file-icon">
                    <LoadingOutlined />
                </span>
                <span v-else class="file-icon">
                    <FileOutlined />
                </span>
                <span class="filename">{{ file.name }}</span>
                <span class="delete-icon" @click="removeFile(file.uid)">
                    <DeleteOutlined />
                </span>
            </li>
        </ul>
    </div>
</template>
<script lang="ts">
import { defineComponent, reactive, ref, computed, PropType } from 'vue'
import { DeleteOutlined, LoadingOutlined, FileOutlined } from '@ant-design/icons-vue'
import axios from 'axios'
import { v4 as uuidv4 } from 'uuid'
import { last } from 'lodash-es'
type UploadStaus = 'ready' | 'loading' | 'success' | 'error'
type FileListType = 'picture' | 'text'
type CheckUpload = (file: File) => boolean | Promise<File>
export interface UploadFile {
    uid: string;
    size: number;
    name: string;
    status: UploadStaus;
    raw: File;
    resp?: any;
    url?: string;
}
export default defineComponent({
    components: {
        DeleteOutlined,
        LoadingOutlined,
        FileOutlined
    },
    props: {
        action: {
            type: String,
            required: true
        },
        beforeUpload: {
            type: Function as PropType<CheckUpload>
        },
        drag: {
            type: Boolean,
            default: false
        },
        autoUpload: {
            type: Boolean,
            default: true
        },
        listType: {
            type: String as PropType<FileListType>,
            defualt: 'text'
        },
        showUploadList: {
            type: Boolean,
            default: true
        }
    },
    emits: ['success', 'error', 'change'],
    setup(props, { emit }) {
        const fileInput = ref<null | HTMLInputElement>(null)
        const filesList = ref<UploadFile[]>([])
        const isDragOver = ref(false)
        const isUploading = computed(() => {
            return filesList.value.some(file => file.status === 'loading')
        })
        const lastFileData = computed(() => {
            const lastFile = last(filesList.value)
            if (lastFile) {
                return {
                    loaded: lastFile.status === 'success',
                    data: lastFile.resp
                }
            }
            return false
        })
        const removeFile = (id: string) => {
            filesList.value = filesList.value.filter(file => file.uid !== id)
        }

        const triggerUpload = () => {
            if (fileInput.value) {
                fileInput.value.click()
            }
        }
        const postFile = (readyFile: UploadFile) => {
            const formData = new FormData()
            formData.append(readyFile.name, readyFile.raw)
            readyFile.status = 'loading'
            axios.post(props.action, formData, {
                headers: {
                    'Content-Type': 'multipart/form-data'
                }
            }).then(resp => {
                readyFile.status = 'success'
                readyFile.resp = resp.data
                emit('success', { resp: resp.data, file: readyFile, list: filesList.value })
            }).catch((e: any) => {
                readyFile.status = 'error'
                emit('error', { error: e, file: readyFile, list: filesList.value })
            }).finally(() => {
                if (fileInput.value) {
                    fileInput.value.value = ''
                }
            })
        }
        // addFileToList
        const addFileToList = (uploadedFile: File) => {
            const fileObj = reactive<UploadFile>({
                uid: uuidv4(),
                size: uploadedFile.size,
                name: uploadedFile.name,
                status: 'ready',
                raw: uploadedFile
            })
            if (props.listType === 'picture') {
                try {
                    fileObj.url = URL.createObjectURL(uploadedFile)
                } catch (err) {
                    console.error('upload File error', err)
                }
                // FileReader to preview local image
                // const fileReader = new FileReader()
                // fileReader.readAsDataURL(uploadedFile)
                // fileReader.addEventListener('load', () => {
                //   fileObj.url = fileReader.result as string
                // })
            }
            filesList.value.push(fileObj)
            if (props.autoUpload) {
                postFile(fileObj)
            }
        }
        const beforeUploadCheck = (files: null | FileList) => {
            if (files) {
                const uploadedFile = files[0]
                if (props.beforeUpload) {
                    const result = props.beforeUpload(uploadedFile)
                    if (result && result instanceof Promise) {
                        result.then(processedFile => {
                            if (processedFile instanceof File) {
                                addFileToList(processedFile)
                            } else {
                                throw new Error('beforeUpload Promise should return File object')
                            }
                        }).catch(e => {
                            console.error(e)
                        })
                    } else if (result === true) {
                        addFileToList(uploadedFile)
                    }
                } else {
                    addFileToList(uploadedFile)
                }
            }
        }
        const uploadFiles = () => {
            filesList.value.filter(file => file.status === 'ready').forEach(readyFile => postFile(readyFile))
        }

        let events: { [key: string]: (e: any) => void } = {
            'click': triggerUpload
        }
        const handleFileChange = (e: Event) => {
            const target = e.target as HTMLInputElement
            beforeUploadCheck(target.files)
        }
        const handleDrag = (e: DragEvent, over: boolean) => {
            e.preventDefault()
            isDragOver.value = over
        }
        const handleDrop = (e: DragEvent) => {
            e.preventDefault()
            isDragOver.value = false
            if (e.dataTransfer) {
                beforeUploadCheck(e.dataTransfer.files)
            }
        }
        if (props.drag) {
            events = {
                ...events,
                'dragover': (e: DragEvent) => { handleDrag(e, true) },
                'dragleave': (e: DragEvent) => { handleDrag(e, false) },
                'drop': handleDrop
            }
        }
        return {
            fileInput,
            handleFileChange,
            isUploading,
            filesList,
            removeFile,
            lastFileData,
            isDragOver,
            events,
            uploadFiles
        }
    }
})
</script>
<style lang="scss">
.upload-list {
    margin: 0;
    padding: 0;
    list-style-type: none;
}

.upload-list li {
    transition: all .5s cubic-bezier(.55, 0, .1, 1);
    font-size: 14px;
    line-height: 1.8;
    margin-top: 5px;
    box-sizing: border-box;
    border-radius: 4px;
    min-width: 200px;
    position: relative;

    &:first-child {
        margin-top: 10px;
    }

    .upload-list-thumbnail {
        vertical-align: middle;
        display: inline-block;
        width: 70px;
        height: 70px;
        position: relative;
        z-index: 1;
        background-color: #fff;
        object-fit: cover;
    }

    .file-icon {
        svg {
            margin-right: 5px;
            color: rgba(0, 0, 0, 0.45);
        }
    }

    .filename {
        margin-left: 5px;
        margin-right: 40px;
    }

    &.upload-error {
        color: #f5222d;

        svg {
            color: #f5222d;
        }
    }

    .file-status {
        display: block;
        position: absolute;
        right: 5px;
        top: 0;
        line-height: inherit;
    }

    .delete-icon {
        display: none;
        position: absolute;
        right: 7px;
        top: 0;
        line-height: inherit;
        cursor: pointer;
    }

    &:hover {
        background-color: #efefef;

        .file-status {
            display: none;
        }

        .delete-icon {
            display: block;
        }
    }
}</style>